Problem: $z=91-27i$ What is the real part of $z$ ?
Solution: Background Complex numbers are numbers of the form $z={a}+{b}i$, where $i$ is the imaginary unit and ${a}$ and ${b}$ are real numbers. [What is the imaginary unit?] The real part of $z$ is denoted by $\text{Re}(z)={a}$. The imaginary part of $z$ is denoted by $\text{Im}(z)={b}.$ Finding the Real and Imaginary Parts of $z$ In this case, $z={91}-{27}i$ is of the form ${a}+{b}i$, where ${a}={91}$ and ${b}={-27}$. Therefore: $\text{Re}(z)={a}={91}$. $\text{Im}(z)={b}={-27}$. Summary The real part of $z$ is ${91}$. The imaginary part of $z$ is ${-27}$.